wristpin needle bearing question

I know juice sells them.

http://juicemotoparts.com/products/high-performance-bronze-bushing-for-motorized-bicycle.html

You might be able to find them elsewhere. That website has a pretty decent bank of information for performance and reliability mods too.

I use the needle bearing in all my engines, but I use a better bearing than what comes in the engine from china factory, some of the stock bearing last the life of the engine without a single problem and others shell out and destroy the piston and jug within a short amount of time, I had one do that to me, but I'm not sure it wa the fault of the bearing or not, I wasn't running as good of an oil then as I am now and I was running a brand new engine really hard without any break in time and it could have been a little on the lean side...shrug...?

But after that all the engines I have built up always get a bearing upgrade just to be on the safer side, one of my oldest BGF ebay engines still has stock bearing and it has over 1000 miles on it now and still running great.

Here is a link to a quality Japan made bearing for a great price with free shipping right to your door here in the USA
http://www.ebay.com/itm/KT101415-IKO-Needle-Roller-Cage-Bearings-10x14x15-Japan-/360844992613

Map

mapbike said:

Here is a link to a quality Japan made bearing for a great price with free shipping right to your door here in the USA
http://www.ebay.com/itm/KT101415-IKO-Needle-Roller-Cage-Bearings-10x14x15-Japan-/360844992613

Map

Click to expand...

is that a replacement wrist pin bearing?? sorry, i just bought an engine from ming and i opened it up and the bearing on the top of the crank looks like a POS brass bushing-doesn't look trustworthy. I think I'm going to get the titanium wrist pin from Juice Motor Parts as well because the wrist pin in this engine looks like another POS as well http://juicemotoparts.com/products/light-wieght-titanium-10mm-wrist-pin-for-49-66-80cc-engines.html

maybe u should try driving it before u remove the pin that is twice the hardness of titainium huh mr engineer

sublunacy said:

maybe u should try driving it before u remove the pin that is twice the hardness of titainium huh mr engineer

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titanium has the highest strength to density ratio of any metallic element. it's as strong as some steels but almost half the weight. i think the purpose of that product is to help lighten the upper part of the crank assembly.

ok i will play.


-piston pin isl HARDENED vs mid grade titainium. 1/0
-aluminum and titainium does not mix. 2/0
- you own a stock pin vs purchased then shipped and installed.....3/0
- must replace pin eventually making it temporary. 4/0
-lighterweight pin is a band-aid for crank vibration. 5/0


---just off the top of my head.

mapbike said:

I use the needle bearing in all my engines, but I use a better bearing than what comes in the engine from china factory, some of the stock bearing last the life of the engine without a single problem and others shell out and destroy the piston and jug within a short amount of time

Click to expand...

What is THE China engine factory you speak of?
Everyone seems to think that EVERY 2-stroke engine is exactly the same with the EXACT same parts in every one.

I have bought all my 2-stroke engines through China Gas made in the Yang Dong factory with high quality Japanese bearings in them, and with ~75 2-stroke builds for local customer not a single one has ever had an issue.

yea lighten up everybody! dong lol

What the heck is with all the aggression in this thread?!?

Seem some have a slight case of DA syndrome in this thread.......lol aggression for no good reason......

I say everyone just do whatever you want with whatever you want, dont pay any attension to anyone elses knowledge based on their personal experiences...... because after all a persons experiences and knowledge gained through trial and error doesnt count for anything or have a piss ants worth of value here or anywhere else for that matter because its a well known fact that no one has ever learned anything from anyone elses experiences, right?

Now all that said...... the bearing I posted a link to here is a good replacement bearing and I would be completely confident with using the titanium wrist pin from juice motors because it may help the engine get a few more rpms before the vibes become uncomfortable, no it wont balance a crank but it's a well kown fact that lightening the piston in these engines does reduce the vibes based on what several have experienced by doing it.

Kcvale, the engine that I had that failed because of the upper bearing was a BGF engine a 66cc slant plug engine that I bought in 2010, dont remember the factory it came from, been way to long, you say the engines you have came with Japanese made bearings, if that is the case that is good, I've only had one upper bearing failure but I have replaced other upper bearings that I could tell just by looking were inferior to the new one I put in, I have yet to see a china girl engine with a bearing stamped or marked that it was actually made in Japan but maybe there are some out there, Ive never owned a grube engine..shrug...!

Map

Avalanche said:

is that a replacement wrist pin bearing?? sorry, i just bought an engine from ming and i opened it up and the bearing on the top of the crank looks like a POS brass bushing-doesn't look trustworthy. I think I'm going to get the titanium wrist pin from Juice Motor Parts as well because the wrist pin in this engine looks like another POS as well http://juicemotoparts.com/products/light-wieght-titanium-10mm-wrist-pin-for-49-66-80cc-engines.html

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Seems I remember someone saying on here they had great service with a brass bushed upper engine, I actually bought a couple bushings from juice to try but never have so far, the bearing link I listed is a good bearing and the titanium wrist pin should be a good upgrade also, and while your in there and have the piston out I'd recommend notching bottom of piston skirt so that when it is at TDC the skirt allows the intake port to be completely open that will allow the air fuel mix to flow in better and could add some noticeable performance if the carb is tuned right and the exhaust is not to restrictive.

Do what you want with your engine, its yours and it doesnt matter what anyone else thinks really, I dont claim to be a know it all with all the mods but I can tell you what I've done and what has worked for me which I learned a big part of from the other fellas and gals on here who have done their share of trial and error testing to see what actually helps and what is just fluff, you may not need a bearing upgrade and then again its kinda like insurance.... you hope you dont need it but if you do your glad you have it, difference with the upper bearing is that when you realize you needed it you have a tore all to heck upper with a ruined cylinder and piston at the least normally.

Best wishes with your engine and just do some digging around on here using the search feature and you'll find many post concerning upper bearing problems questions and what people have done.

Peace, map

A bushing motor will not destroy a top end with debris when it goes. This is why some people swear by the bushings in china motors. I much prefer the needle bearing version myself, but I've never lost a motor from sucking a chunk of failed bearing through the top end. I really don't care on a chinagirl if it works.
There are many chainsaw brands with good quality needle bearings available in the china sizes for those who desire better reliability. Stihl makes a couple, and I think there are some moped brands such as Gilardoni that interchange as well. Search it. There are members here who know what fits and where to get one.
A better quality needle bearing and/or piston pin will always be a good investment no matter WHAT the stock engine has.
Lighter is better. Stronger is better. Always will be.

One of my engines vibrate tons more than the rest,about 20mph.
I like the idea of a titanium wrist pin and a brass bushing...wonder if those bushings get lube as well as the rollers...looks like they have oil grooves.

60weight said:

One of my engines vibrate tons more than the rest,about 20mph.
I like the idea of a titanium wrist pin and a brass bushing...wonder if those bushings get lube as well as the rollers...looks like they have oil grooves.

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If it bothers you, it would be quite easy to drill some lubrication holes in the rod and bushing. Common mod in the old days.
Also works on roller bearings. Just be sure to properly chamfer the holes and be sure it's smooth inside.

60weight said:

One of my engines vibrate tons more than the rest,about 20mph.
I like the idea of a titanium wrist pin and a brass bushing...wonder if those bushings get lube as well as the rollers...looks like they have oil grooves.

Click to expand...

I would recommend a quality needle bearing and notch piston skirt to clear intake port better which will take an additional amount of weight off the top end and could give you more rpms before the serious vibes kick in, sometimes making the top end a little lighter and the balance is improved some.

I edited this post and removed my endorsement of the titanium pin and bushing... not a good idea since mine failed quickly..!

Map

One of my engines is a bgf 48cc that the piston didn't fully clear the intake port, after trimming the piston the engine vibrates very little. Most that run the 66 and the 48 say the 66 tends to vibrate more.

Greg58 said:

One of my engines is a bgf 48cc that the piston didn't fully clear the intake port, after trimming the piston the engine vibrates very little. Most that run the 66 and the 48 say the 66 tends to vibrate more.

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66cc has larger bore, this means heavier piston which is why I think its a good idea to lighten the piston, I've never had a 48cc engine but I have always thought that the reason many people say they're smoother running engines is because of the smaller lighter piston, since is seems the 66cc is just a big bore 48cc and the crankshaft was not changed in any way to accommodate the extra weight of the 66cc piston, just my thoughts on the matter, I could be wrong but it seems to me like its a good possibility.

mapbike said:

66cc has larger bore, this means heavier piston which is why I think its a good idea to lighten the piston, I've never had a 48cc engine but I have always thought that the reason many people say they're smoother running engines is because of the smaller lighter piston, since is seems the 66cc is just a big bore 48cc and the crankshaft was not changed in any way to accommodate the extra weight of the 66cc piston, just my thoughts on the matter, I could be wrong but it seems to me like its a good possibility.

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I agree. I think the 66cc displacement piston and rod was simply added on to the existing 49cc bottom end with very few changes. I think the new generation of better balanced motors are just now getting cranks balanced to swing the bigger 66cc arm. I've noticed some small changes in the transfer port casting in the case as well.
The 49's feel a bit smoother on top but a bit weaker on the bottom end. The 66 has more grunt. From the midrange up, there is very little difference, with the bigger motor shaking harder as it tops out and the 49 pulling a bit longer before it gets unhappy.
In the real world, there is very little difference aside from vibration levels.

maniac57 said:

I agree. I think the 66cc displacement piston and rod was simply added on to the existing 49cc bottom end with very few changes. I think the new generation of better balanced motors are just now getting cranks balanced to swing the bigger 66cc arm. I've noticed some small changes in the transfer port casting in the case as well.
The 49's feel a bit smoother on top but a bit weaker on the bottom end. The 66 has more grunt. From the midrange up, there is very little difference, with the bigger motor shaking harder as it tops out and the 49 pulling a bit longer before it gets unhappy.
In the real world, there is very little difference aside from vibration levels.

Click to expand...

At some point I will likely buy a F50 from dax and do the same port work and trim the piston skirt like I did to my last Gen IV 66cc just to see what differences I notice between the two.

Map